The present invention relates to containers for holding and storing bulk materials. More particularly, the present invention relates to air-breathable containers that facilitate communication from the container of moisture emitted from bulk materials such as leaf products held in the container for drying and long-term storage.
Large-volume containers are often used for holding, storing, and transporting bulk materials, such as powders, leaf and root crop products, metal castings, plastic resins, and many other materials. Generally, the containers provide sturdy walls for protecting the bulk materials while allowing the containers to be handled by equipment such as fork lift trucks and platen trucks. The containers are also often stacked in warehouses.
Some containers also facilitate the drying and curing of the bulk materials. For example, some leaf products are held in containers made with wood-slats that are secured together with enwrapping metal bands. There are gaps between adjacent edges of the wood slats in the wall of the container. As the leaf products emit moisture and dry, the moisture communicates from the container through the gaps to the atmosphere. The escape of the moisture prevents mold from attacking the leaf products. These containers also allow for long-term storage of the leaf products. This enables the products to cure to useful raw material. The containers have sturdy walls which enable the containers to be stacked for storage in warehouses.
Since the total weight of a single loaded container may run as high as fifteen hundred (1500) pounds, the packing and shipping of bulk materials presents several unique problems. One problem is that such bulk materials are typically poured or thrown into the container and shipped loose so that the packed materials xe2x80x9cflowxe2x80x9d about the interior of the container. Materials of lesser densities may be pressed or compacted during filling of the container. After filling, the memory of the packed material exerts an outward force on the side walls of the pack. The side walls of the container must be sufficiently rigid in the horizontal plane to withstand internal movement or expansion of the materials and thereby must resist against bulging as a result of internal material flow. Another problem is that the side walls of the container must also be sufficiently rigid to permit stacking of one container on top of another. The side walls must provide sufficient compression strength to prevent any deformation or collapse of the container when others are stacked upon it.
U.S. Pat. No. 4,635,815 discloses a corrugated paperboard container having an exterior tubular corrugated paperboard body laminated to an interior tubular corrugated paperboard body, and includes a plurality of support members fixedly secured between the exterior and interior bodies so as to reinforce the container. While this container has been successful in long-term storage of bulk materials, it has not been gainfully used with fresh leaf products. The corrugated paperboard would prevent escape of moisture from the container. The leaf products would become damaged by mold and decay which leads to lost value. The leaf products must first dry by removal of the moisture held in the leaf products before long term storage can be made successfully with paperboard-type containers. However, transfer of such leaf products from the wood slat containers to the corrugated paperboard container after drying is not efficient. The wood slat containers have drawbacks to their continued use for leaf products. These problems include the costs and availability of such containers.
Our U.S. Pat. No. 6,126,067 describes a corrugated paperboard container having at least one side panel with a plurality of openings defined by drilling through the side panel with a non-fluted drill, whereby the openings provide for communicating moisture through the panel and outwardly of the container. While this container satisfactorily facilitates drying of leaf products, some believe there are drawbacks which may limit the use of such containers. Particularly, the open flutes in the corrugated side panel may become occluded such as with dust particles carried by the communicated air, and the effectiveness of the container for drying leaf products may be reduced.
Accordingly, there is a need in the art for an improved air-breathable container that facilitates communication from the container of moisture emitted from the leaf products held in the container for drying and long-term storage. It is to such that the present invention is directed.
The present invention solves the above-described problems in the prior art by providing a container that facilitates communication of moisture from the container for drying and long-term storage of leaf products. The container comprises a blank of a sheet material scored to define two opposing end panels and two opposing side panels. The blank is foldable on the scores and a pair of opposing distal ends are adhered together to define a tubular body openable from a first position which is substantially flat to a second position squared-open for receiving a plurality of leaf products within a cavity defined by the opposing end and side panels. At least one of the panels includes a field of spaced-apart passageways defined by conical pins pushed through the side wall in a first direction and a second opposing direction whereby sheet material from the fiber board in the corrugated paper and sheet is disposed as a lining for the passageways for communicating moisture through the panel. A bottom closes a first open end of the tubular body and a top cap closes a second open end of the tubular body. The leaf products, being held within the tubular body, emit moisture which communicates through the passageways in the panel to atmosphere for drying and long-term storage of the leaf products.
A second embodiment of the present invention includes an outer wall-forming blank of corrugated paperboard scored to provide a series of wall panels foldably joined together and a second wall-forming blank of corrugated paperboard also scored to provide a series of wall panels foldably joined together. The second wall-forming blank is formed for bonding to the inside surface of the first wall-forming blank. A plurality of support members are fixedly retained between the first wall-forming blank and the second wall-forming blank, with at least one support member being provided on each wall of the container. Further, a plurality of corrugated sheets are secured between both the first wall forming blank and the second wall forming blank. At least one of the walls defined by the blanks defines a field of spaced-apart passageways for communicating moisture through the wall. The passageways are defined by conical pins pushed through the side wall in a first direction and a second opposing direction whereby sheet material of the fiberboard layers in the wall is disposed within the passageway as a lining for the passageway for communicating moisture through the panel. The unitary container accordingly facilitates communication of moisture from leaf products to atmosphere while reinforced side walls provide compression strength and prevent against any bulging.
In another aspect, the present invention provides a method of defining passageways in a side wall of a container for drying and long-term storage of leaf products, comprising the steps of:
(a) receiving a blank of a sheet material between aligned opposing first and second plates each defining a plurality of spaced-apart openings, the blank scored to define two opposing end panels and two opposing side panels, foldable on the scores and a pair of opposing distal ends thereof adhered together to define a tubular body openable from a first position which is substantially flat to a second position squared-open for receiving a plurality of leaf products within a cavity defined by the opposing end and side panels;
(b) moving a first array of conical pins from a retracted position to an extended position through the openings in the first plate with the conical pins extending substantially to a mid-point of the thickness of the blank to define a portion of passageways through the blank; and
(c) moving a second array of conical pins from a retracted position to an extended position through the openings in the second plate with the conical pins extending substantially to a mid-point of the thickness of the blank to define a second portion of passageways through the blank,
whereby leaf products, being held within the tubular body, emit moisture which communicates through the field of passageways in the panel to atmosphere for drying and long-term storage of the leaf products.